6-1
6.
INTERPRETING THE DISPLAY
6.1 Bottom
Echo
When the tilt angle is changed, the bottom echo will appear on the screen. When
the tilt angle is decreased, the bottom trace becomes wider and weaker. By
observing the bottom condition on the screen, the skipper can prevent the net
from being damaged by a reef or a shipwreck.
(A) Flat bottom
Tilt angle: 10˚ to 15˚
(B) Flat bottom
Tilt angle: 20˚ or more
(C) Sloping bottom
Tilt angle: 20˚ or more
Bottom
Shallow bottom
is displayed in
a strong color
and with a
short tail.
Bottom is displayed
narrower and in
stronger colors when
compared to (A).
Decreased tilt angle
Only half of
vertical beam width
captures the bottom.
The deeper, sloping
bottom echo is displayed
in a weak color and
with a long tail.
Bottom echoes
